The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform
Tom B. Letessier - One of the best experts on this subject based on the ideXlab platform.
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Climate Oscillation and the invasion of alien species influence the oceanic distribution of seabirds
Ecology and Evolution, 2020Co-Authors: Peter Carr, Jessica J. Meeuwig, Tom B. Letessier, Julian Perezcorrea, Peter Carr, Heather J KoldeweyAbstract:Spatial and temporal distribution of seabird transiting and foraging at sea is an important consideration for marine conservation planning. Using at-sea observations of seabirds (n = 317), collected during the breeding season from 2012 to 2016, we built boosted regression tree (BRT) models to identify relationships between numerically dominant seabird species (red-footed booby, brown noddy, white tern, and wedge-tailed shearwater), geomorphology, oceanographic variability, and Climate Oscillation in the Chagos Archipelago. We documented positive relationships between red-footed booby and wedge-tailed shearwater abundance with the strength in the Indian Ocean Dipole, as represented by the Dipole Mode Index (6.7% and 23.7% contribution, respectively). The abundance of red-footed boobies, brown noddies, and white terns declined abruptly with greater distance to island (17.6%, 34.1%, and 41.1% contribution, respectively). We further quantified the effects of proximity to rat-free and rat-invaded islands on seabird distribution at sea and identified breaking point distribution thresholds. We detected areas of increased abundance at sea and habitat use-age under a scenario where rats are eradicated from invaded nearby islands and recolonized by seabirds. Following rat eradication, abundance at sea of red-footed booby, brown noddy, and white terns increased by 14%, 17%, and 3%, respectively, with no important increase detected for shearwaters. Our results have implication for seabird conservation and island restoration. Climate Oscillations may cause shifts in seabird distribution, possibly through changes in regional productivity and prey distribution. Invasive species eradications and subsequent island recolonization can lead to greater access for seabirds to areas at sea, due to increased foraging or transiting through, potentially leading to distribution gains and increased competition. Our approach predicting distribution after successful eradications enables anticipatory threat mitigation in these areas, minimizing competition between colonies and thereby maximizing the risk of success and the conservation impact of eradication programs.
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Climate Oscillation and the invasion of alien species influence the oceanic distribution of seabirds
Authorea, 2020Co-Authors: Julian Perez-correa, Peter Carr, Jessica J. Meeuwig, Heather J. Koldewey, Tom B. LetessierAbstract:Aim: We aim to document the extent to which Climate Oscillation and rat infestation on islands affect the distribution of seabirds at sea. Location: The Chagos Archipelago, British Indian Ocean Territory, Central Indian Ocean Methods: At sea observations of seabirds (n = 425) were collected from 2012 to 2017 during the breeding season. We used generalized additive models to identify relationships between dominant seabird families (Laridae, Sulidae, and Procellariidae), geomorphology, oceanographic variability, and Climate Oscillation. We built boosted regression trees to quantify the effects of proximity to both rat-free and rat-infested islands on seabird distribution, identifying breaking point thresholds in distribution. Results: We identified oceanic hotspots and common geomorphic and oceanographic drivers for all seabird families. We documented positive relationships between Sulidae and Procellariidae abundance and the Indian Ocean Dipole, as represented by the Dipole Mode Index. The abundance of Laridae and Sulidae declined abruptly with greater distance to island. Both families aggregated more densely (1.08 and 1.25 times higher respectively) and in greater proximity (distribution thresholds at 16 and 44 km closer to islands, respectively) next to rat-free island compared with to rat-infested islands. In contrast, Procellariidae increased in abundance with greater distance to islands, plateauing at 83 km and were not significantly influenced by rat presence on nearby islands. We identified areas of increased abundance at sea under a scenario where rats are eradicated from infested islands with subsequent seabird recolonization. Main conclusions: Climate Oscillations may cause shifts in seabird distribution, possibly through changes in regional productivity and prey distribution. Invasive species eradications and subsequent island recolonization can lead to predictable distribution gains and increased competition. Our analysis predicting range extension after successful eradications enables anticipatory threat-mitigation in these areas, minimising competition between colonies and thereby maximising the risk of success and the conservation impact of eradication programmes.
Julian Perezcorrea - One of the best experts on this subject based on the ideXlab platform.
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Climate Oscillation and the invasion of alien species influence the oceanic distribution of seabirds
Ecology and Evolution, 2020Co-Authors: Peter Carr, Jessica J. Meeuwig, Tom B. Letessier, Julian Perezcorrea, Peter Carr, Heather J KoldeweyAbstract:Spatial and temporal distribution of seabird transiting and foraging at sea is an important consideration for marine conservation planning. Using at-sea observations of seabirds (n = 317), collected during the breeding season from 2012 to 2016, we built boosted regression tree (BRT) models to identify relationships between numerically dominant seabird species (red-footed booby, brown noddy, white tern, and wedge-tailed shearwater), geomorphology, oceanographic variability, and Climate Oscillation in the Chagos Archipelago. We documented positive relationships between red-footed booby and wedge-tailed shearwater abundance with the strength in the Indian Ocean Dipole, as represented by the Dipole Mode Index (6.7% and 23.7% contribution, respectively). The abundance of red-footed boobies, brown noddies, and white terns declined abruptly with greater distance to island (17.6%, 34.1%, and 41.1% contribution, respectively). We further quantified the effects of proximity to rat-free and rat-invaded islands on seabird distribution at sea and identified breaking point distribution thresholds. We detected areas of increased abundance at sea and habitat use-age under a scenario where rats are eradicated from invaded nearby islands and recolonized by seabirds. Following rat eradication, abundance at sea of red-footed booby, brown noddy, and white terns increased by 14%, 17%, and 3%, respectively, with no important increase detected for shearwaters. Our results have implication for seabird conservation and island restoration. Climate Oscillations may cause shifts in seabird distribution, possibly through changes in regional productivity and prey distribution. Invasive species eradications and subsequent island recolonization can lead to greater access for seabirds to areas at sea, due to increased foraging or transiting through, potentially leading to distribution gains and increased competition. Our approach predicting distribution after successful eradications enables anticipatory threat mitigation in these areas, minimizing competition between colonies and thereby maximizing the risk of success and the conservation impact of eradication programs.
Heather J Koldewey - One of the best experts on this subject based on the ideXlab platform.
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Climate Oscillation and the invasion of alien species influence the oceanic distribution of seabirds
Ecology and Evolution, 2020Co-Authors: Peter Carr, Jessica J. Meeuwig, Tom B. Letessier, Julian Perezcorrea, Peter Carr, Heather J KoldeweyAbstract:Spatial and temporal distribution of seabird transiting and foraging at sea is an important consideration for marine conservation planning. Using at-sea observations of seabirds (n = 317), collected during the breeding season from 2012 to 2016, we built boosted regression tree (BRT) models to identify relationships between numerically dominant seabird species (red-footed booby, brown noddy, white tern, and wedge-tailed shearwater), geomorphology, oceanographic variability, and Climate Oscillation in the Chagos Archipelago. We documented positive relationships between red-footed booby and wedge-tailed shearwater abundance with the strength in the Indian Ocean Dipole, as represented by the Dipole Mode Index (6.7% and 23.7% contribution, respectively). The abundance of red-footed boobies, brown noddies, and white terns declined abruptly with greater distance to island (17.6%, 34.1%, and 41.1% contribution, respectively). We further quantified the effects of proximity to rat-free and rat-invaded islands on seabird distribution at sea and identified breaking point distribution thresholds. We detected areas of increased abundance at sea and habitat use-age under a scenario where rats are eradicated from invaded nearby islands and recolonized by seabirds. Following rat eradication, abundance at sea of red-footed booby, brown noddy, and white terns increased by 14%, 17%, and 3%, respectively, with no important increase detected for shearwaters. Our results have implication for seabird conservation and island restoration. Climate Oscillations may cause shifts in seabird distribution, possibly through changes in regional productivity and prey distribution. Invasive species eradications and subsequent island recolonization can lead to greater access for seabirds to areas at sea, due to increased foraging or transiting through, potentially leading to distribution gains and increased competition. Our approach predicting distribution after successful eradications enables anticipatory threat mitigation in these areas, minimizing competition between colonies and thereby maximizing the risk of success and the conservation impact of eradication programs.
David W Pearce - One of the best experts on this subject based on the ideXlab platform.
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hydrologic linkages between a Climate Oscillation river flows growth and wood δ13c of male and female cottonwood trees
Plant Cell and Environment, 2013Co-Authors: Stewart B. Rood, Karen M. Gill, Sobadini Kaluthota, Deborah J Ball, Matthew G Letts, David W PearceAbstract:: To investigate climatic influence on floodplain trees, we analysed interannual correspondences between the Pacific Decadal Oscillation (PDO), river and groundwater hydrology, and growth and wood (13)C discrimination (Δ(13)C) of narrowleaf cottonwoods (Populus angustifolia) in a semi-arid prairie region. From the Rocky Mountain headwaters, river discharge (Q) was coordinated with the PDO (1910-2008: r(2) = 0.46); this pattern extended to the prairie and was amplified by water withdrawal for irrigation. Floodplain groundwater depth was correlated with river stage (r(2) = 0.96), and the cottonwood trunk basal area growth was coordinated with current- and prior-year Q (1992-2008: r(2) = 0.51), increasing in the mid-1990s, and decreasing in 2000 and 2001. Annual Δ(13)C decreased during low-flow years, especially in trees that were higher or further from the river, suggesting drought stress and stomatal closure, and male trees were more responsive than females (-0.86 versus -0.43‰). With subsequently increased flows, Δ(13)C increased and growth recovered. This demonstrated the linkages between hydroclimatic variation and cottonwood ecophysiology, and we conclude that cottonwoods will be vulnerable to drought from declining river flows due to water withdrawal and Climate change. Trees further from the river could be especially affected, leading to narrowing of floodplain forests along some rivers.
Wuhui Duan - One of the best experts on this subject based on the ideXlab platform.
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timing and structure of termination ii in north china constrained by a precisely dated stalagmite record
Earth and Planetary Science Letters, 2019Co-Authors: Wuhui Duan, Hai Cheng, Ming Tan, Lawrence R EdwardsAbstract:Abstract The timing and structure of Termination II (T-II) is still debatable as the number of high-quality records is insufficient. This study presents precisely dated stalagmite δ 18 O data between 133.4 ± 0.3 to 126.6 ± 0.3 ka BP (covering most of T-II) from north China, near the northern limit of the East Asian summer monsoon (EASM), an area sensitive to Climate change. The onset of the last interglacial is constrained at 129.4 ± 0.3 ka BP, consistent with south Chinese speleothem records, further supporting the idea that Northern Hemisphere summer insolation plays an important role in initiating glacial terminations. An extended interval of heavy δ 18 O is observed immediately prior to this abrupt transition, named as the “Weak Monsoon Interval” (WMI) in south Chinese cave records, which was associated with the Heinrich Stadial 11 (H11) in the North Atlantic. A significant millennial-scale interstadial peaking at 132.7 ± 0.3 ka BP is identified preceding the weakest phase of the WMI. A synchronous counterpart is also found in some south Chinese speleothem and North Atlantic alkenone Mg/Ca SST records. It is inferred that the main H11 freshwater penetration possibly occurred after 131.5 ka BP, leaving some aspects of ocean and atmospheric circulation still in interstadial mode from 134 to 131.5 ka BP. Following the onset of the last interglacial, there was a millennial-scale “pause” in our δ 18 O record, synchronized with a “slowdown” in the rate of decrease in δ 18 O in south Chinese cave records. This is possibly a large regional Climate Oscillation, as it is also identified in some North Atlantic records, but one which is too weak to be a Younger Dryas (YD)-type event. In summary, compared to south Chinese cave records, significant millennial-scale Climate Oscillations before and after the synchronous onset of the last interglacial is the main feature of our record. Nevertheless, the sequence of these Climate events remains very different from Termination I (T-I), which is possibly ascribed to the stronger insolation, higher atmosphere CO2, and the resultant faster and greater meltwater pulse to the North Atlantic during T-II than during T-I.